Circuit breaker and transformer protected thereby



Oct. 19, 1965 M. G. LEONARD CIRCUIT BREAKER AND TRANSFORMER PROTECTED THEREBY Filed OGC. 4, 1957 3 Sheets-Sheet 2 Fig. 3.

Oct. 19, 1965 M. G. LEONARD 3,213,248

CIRCUIT BREAKER ANC TRANSFCRMER PROTECTED THEREBY Filed oct. 4, 1957 s sheets-sheet s Fig.4.

United States Patent C) 3,213,248 CTRCUIT BREAKER AND TRANSFORMER PROTECTED THEREBY Merrill G. Leonard, Fowler, Ohio, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 4, 1957, Ser. No. 688,294 12 Claims. (Cl. ZOO-116) This invention relates to circuit breakers and more particularly to circuit breakers for use in distribution transformers, and to the protection of such transformers by circuit breakers.

An object of the invention is to provide a circuit breaker embodying a trip device operable in response to overload conditions to trip the circuit breaker with settable means to prevent tripping the circuit breaker open.

Another object of the invention is to provide a circuit breaker for use in a distribution transformer having a trip device for tripping the breaker open, including a biased trip actuator with means for preventing operation of said trip actuator to trip the breaker.

A further object of the invention is to provide a circuit breaker having a single current-responsive element movable to one position to cause operation of a signal or indicating device and then movable in the same direction to a further position to trip the breaker, with manually operable mechanism for preventing tripping of the breaker without interfering with operation of the signal or indicating device. This makes it possible to manually set the circuit breaker so that it will not open in situations where it is important that there should be no interruption in the electrical service, but at the same time the signal device operates to give an indication that there has been an overload so that corrective action may be taken.

It is a further feature of the invention, that the operating handle of the circuit breaker which is provided for opening and closing the contacts may also be operated to reset the signal device, without opening the contacts and causing a service interruption, at the same time that the breaker has been manually set to not trip open automatically in response to overloads. This makes it possible to reset the signal device one or more times and if the signal device is actuated several times, it indicates that the overload was not merely transient but is of a permanent or recurring nature. Thus, while the breaker has been set to remain closed, it will be possible without a service interruption to determine the presence of an abnormal condition and to determine whether it is of a transient or recurring nature, and at the same time the handle may be operated to open and close the breaker and use it as a switch, so that the circuit may be opened manually at a particular time when it has been determined that a service interruption may be tolerated without serious consequences, particularly if an electrician or lineman is then available with the necessary equipment to take steps to prevent recurrence of the abnormal condition and restore service with a minimum of delay before there has been time for substantial damage, such for example as the spoilage of food in an electric freezer.

Another illustration of the need for this invention is in the case of a transformer supplying a theater or auditorium where a service interruption putting out the lights during a program in the filled auditorium could cause a panic. Merely raising the calibration of the breaker in the transformer while the program is in progress, is not a good solution because that also raises the calibration of the signal device so that it would not give proper indication of the occurrence of an overload condition, and in addition there could still be a service interruption if there were an even heavier overload. With the invention dislCC closed herein, the circuit breaker in the transformer can be manually set for the duration of the program so that the breaker will not open the circuit automatically, but the signal light will still give early warning of the existence of an overload. Steps may then be taken to reduce the load by turning off some circuits or to temporarily correct the abnormal condition, without having all of the lights extinguished. After the program is over and the audience has left the auditorium, the circuit may be safely opened manually and the trouble may be fixed or an additional or larger transformer may be installed to carry the heavier than anticipated load.

Thus, another object of the invention is to provide a circuit-breaker-protected distribution transformer embodying a trip device operable in response to overload currents to trip the breaker open with an interposer positionable from the outside of the transformer housing to prevent operation of the trip device to trip the breaker open and thereby maintain the transformer in service.

An additional object of the invention is to make possible a completely-self-protected transformer having primary and secondary coils and a circuit breaker within the tank or housing of the transformer, with means at the outside of the tank (l) which signals an indication when an overload condition is approached or has occurred, (2) which may be manually set in one position to prevent automatic opening of the circuit from the transformer and in another position to provide for automatic opening of the circuit during overload or short-circuit conditions and (3) which may be manually operated to reset the signal device without opening the circuit and also manually operated to open and close the circuit, if that is desired, even though automatic opening of the circuit may be prevented. A fourth feature which is preferably provided, but which may be optionally omitted for some applications, is in the provision of additional means operable from the outside of the transformer for raising the calibration of the circuit opening and/or signaling mechanism, as may be desired.

The invention, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

FIGURE 1 is an elevational view of a circuit breaker embodying the principles of .the invention;

FIG. 2 is an elevational view showing the overload indicating device;

FIG. 3 is a top plan view showing two circuit breakers of the type shown in FIG. l and the controls therefor; and

FIG. 4 is an elevational sectional view of a distribution transformer showing the circuit breaker and its controls mounted therein.

The invention is illustrated as applied to a transformer using a circuit breaker of the type disclosed in Patent No. 2,686,242 issued August l0, 1954 to Merrill G. Leonard and Arthur M. Loekie, and assigned to the assignee of the present invention. rThis patent may be referred to for a more detailed disclosure of parts of the circuit breaker.

Referring to FIG. l of the drawings, the circuit breaker which protects the transformer comprises a base or housing member 11 of molded insulating material on which are mounted the parts of the breaker mechanism which include a stationary contact 13, a movable contact 15, operating mechanism indicated generally at 17 and a trip device indicated generally at 19. The stationary contact .13 is mounted on one leg of a U-shaped slide 21 which 1s biased by a spring 22 to provide Contact pressure in the closed position of the contacts.

The movable contact is rigidly mounted on a U- shaped member 31 which is pivotally mounted by a pivot pin 33 on one end of a iloating switch arm 35 for limited movement relative thereto to provide contact alignment in the closed-contact position. The switch arm 35 at its upper end (FIG. 1) is formed as at 37 to provide a latch surface for engaging a latch surface 39 on a pivoted latch member 41. A spring 43 is connected under tension between the portion 37 of the switch arm and a spring stud 45 to bias the switch arm in opening direction about a pivot pin 47 when the latch member 41 is actuated to release the switch arm. Mounted on the pin 47 is a roller 51 which engages in a generally triangular opening 53 in the base or `frame 11. The roller 51 is guided between two arcuate guide surfaces 52 and 54 at the left end of the opening 53. The guide surfaces 52 and 54 are generally concentric with the latch portion 39 so that the oating switch arm 35 is guided for pivotal movement about its end 37 and is held against longitudinal movement. A link 55 is pivotally mounted on the pin 47 and has a roller 61 mounted on a pin 59 at its other end. The roller 61 cooperates with an arcuate surface 63 of the opening 53.

An operating handle 65 of molded insulating material has an arcuate portion 67 molded integral therewith and adapted to slide on an arcuate surface 69 on a portion 70 of the base 11 between On and O11 positions. Operating spring means 71 is connected under tension between the handle 65 and the pin 59.

In the On position of the handle 65, the line of force of the operating spring 71 is below a line drawn through the centers of the pins 47 and 59 thus biasing the roller 61 into the lower right-hand portion of the opening 53, and, through the link 55, holds the roller 51 in the lefthand end of the opening 53 thus holding the switch arm 35 in the closed position. Also, in the On position of the handle 65, the line of force of the spring 71 is below the center about which the arcuate surface 69 is drawn and about which the handle moves, thus biasing the handle to the On position.

When the operating handle 65 is moved upwardly from the On position, it moves the line of force of the spring 71 above the lines 47-59 at which time a component of the force of the spring biases the roller 61 upwardly and causes the roller together with the end of the link 55 to move upwardly along the arcuate surface 63 and toward the right with a snap action, the roller 61 being arrested by engagement with the upper right-hand end of the opening 53. During this movement, the spring 71 acts through the link 55 to move the switch arm 35 to the open position with a snap action. During the opening movement, the switch arm 35 pivots about the point 39 and its opening movement is arrested by engagement with a portion 83 of the base 11.

The breaker contacts are closed by downward movement of the handle to the On position, during which movement the line of force of the spring 71 passes an overcenter point, at which time the spring biases the roller 61 downwardly and causes it to move down along the surface 63 to the lower position. This movement of the roller 61 acts through the link 55 to close the contacts with a snap action.

The switch member 35 is automatically moved to the open position by the spring 43 upon actuation of the latch member 41 which is effected by the trip device 19. The latch 41 is pivoted on a pin 89 in the base 11 and is biased by a spring 91 to latching position to releasably restrain the switch arm 35 in the closed position. When the latch member 41 is actuated to unlatched position, releasing the upper end of the switch arm 35, the spring 43 acts to rotate the switch arm about the pin 47 to the open position to effect opening of the contacts.

In addition to the latch member 41, the trip device includes a U-shaped latch actuator 93 pivoted on a pin 95 and biased by a spring 97 in a clockwise direction One arm 99 of the latch actuator 93 normally is engaged by a latch portion 100 of a latch element 101 which is an extension rigidly mounted on the free end of a bimetal element 103, and releasably holds the latch actuator in operative position. The other arm of the latch actuator has a projection 107 thereon adapted to engage an ear 109 formed on the end of the latch member 41 and actuate the latter upon release of the actuator 93. The two arms 99 and 105 of the latch actuator 93 are connected by an integral yoke portion 111 to which one end of the spring 97 is attached7 the other end of the spring being hooked over a stud 113 in the base 11.

The bimetal element 103 is rigidly mounted on a yoke member 115, the legs of which are pivotally supported on a pin 117 mounted in a boss 119 of the base 11. One leg 121 of the yoke 115 extends to the right from the pivot 117 and has its free end pivotally connected by a pin 123 to the inner end of an adjusting rod 125 which extends out through an opening in the top portion of the base 11 and has a long internally threaded screw 127 threaded onto the outer end thereof. A spring 129 biases the yoke member and the bimetal element in a clockwise direction about the pivot 117. The inner end of the adjusting screw 127 bears against `the top wall of the base 11 and by turning the screw 127 the bimetal assemblage may be moved to adjust the amount of overlap of the latch 100 and thereby vary the tripping time-current characteristic of the breaker.

A ilexible terminal conductor is attached to the yoke 115 which is in turn connected to the bimetal to connect the breaker in an external electric circuit. A exible conductor 141 connects the free end of the bimetal element to the adjacent end of the switch arm 35 and a flexible conductor 143 is connected to the stationary contact for connecting the breaker in an electric circuit.

When an overload current occurs in the circuit through the breaker, the bimetal element 103 becomes heated and when heated a predetermined amount, bends upwardly causing the latch 100 to release the latch actuator 93 whereupon the spring 97 snaps the actuator sharply clockwise causing the projection 107 to strike the ear 109 on the latch member 41 and move this element to unlatching position releasing the upper end of the switch arm 35. The spring 43 then moves the switch arm 35 about the pivot 47 to the open position.

The mechanism is reset and relatched following an automatic opening operation by moving the handle 65 to the Off position. This moves the switch member 35 to the manually open position, moving the upper end of the switch arm and the latch portion 37 to the right of the latch surface 39 on the latch member 41 and permitting the spring 91 to restore this member to the latching position. As the handle 65 nears the Ofr position, it engages a surface 145 on the latch actuator 93 and rotates the latch actuator counterclockwise to efrect relatching of the actuator by the extension 101 on the bimetal 103. The contacts are then closed in the previously described manner by movement of the handle to the On position.

An indicating or signal device is provided to indicate the presence of an overload condition that is not of sufficient magnitude to trip the breaker open but which gives an indication that the current in the circuit is approaching a dangerous overload condition, or that a dangerous condition has existed and has cleared itself without tripping the breaker. The indicating device also indicates that the breaker has tripped `open in response to an overload condition.

The indicating means comprises a releasahle signal member 147 (FIG. 2) pivotally supported on a pin 149 mounted on an adjustable slide 151. The member 147 is provided with a latch portion 153 which normally engages and is releasably restrained by the latch portion 100 of the extension or latch member 101 carried by the bimetal element 153. An arm 155 of the releasable member 147 is pivotally connected by a pivot pin 157 to a slidable Contact carrying rod 159 of insulating material. The contact rod 159 is guided for vertical sliding movement by spaced projections 161 on the base 11. A tapered bridging contact 163 is threaded into a tapped hole in Ithe upper end of the rod 159 and is locked in adjusted position by means of a lock nut 165. A spring 167 biases the member 147 in a clockwise direction thereby biasing the contact rod 159 upwardly to engage the bridging contact 163 with a pair of spaced conductors 169 (FIGS. 1 and 2) thereby establishing a circuit for energizing a visual or audible signal means. The conductors or contact members 169 extend or are connected through both pole units of the breaker so that a circuit is completed through them upon movement of the bridging contact 163 of either pole unit.

The slide 151 is disposed for vertical movement in a groove formed by portions 171 and 173 integral with the base 11. At its upper end, the slide 151 has an ear 175 formed thereon through an opening in which extends an adjusting screw 177 (FIG. 2). A threaded portion of the adjusting screw 177 engages a threaded opening in an angular portion 179 of the slide 151 and the reduced inner end of the screw 177 bears in an opening in a rib 181 on the base 11. The adjusting screw 177 extends out through an opening in the top wall of the base 11 and the head of the screw 177 bears against the base. A compression spring 183 biases the slide 151, the screw 177 and the releasable member 147 downwardly. Turning the screw 177 bodily moves the slide 151 and the releasable member 147 to vary the latch overlap and thus vary the unlatching time of the releasable member.

The releasable member 147 is reset and relatched following an operation thereof by movement of the handle 65 (FIG. l) part way toward the Ott position but without moving the handle far enough to cause opening of the breaker contacts. The releasable member 147 is provided with a curved, downwardly extending arm 187 (FIGS. 1 and 2) having a cam surface 139 (FIG. l) thereon which is engaged by the handle to reset the signal device.

As illustrated in FIG. 3 of the drawings, two or more of the circuit breakers can be mechanically tied together in a suitable manner for unitary operation to control a multi-phase circuit. When two 4or more breakers are tied together, a common trip bar 201 (FIG. 1) is provided and rigidly secured to the latch members 41 for all of the breakers so Ithat tripping operation of the latch member 41 for any one of the breakers in response to an overload current in the related phase circuit will operate the latch members 41 of all of the breakers.

The circuit breaker, shown generally at 23 (FIG. 4), is mounted in a transformer tank housing 25 having a cover 27 through which extend bushings 29 for connecting the primary winding 75 on the iron core 77 of a transformer shown generally at 73 in a distribution circuit. Bushings 57 are provided in the side of the tank or housing 25 for connecting the secondary winding 79 of the transformer to a load circuit. The two poles of the breaker 23 are connected respectively in two of the connections 85 from the terminal bushings 57 to the secondary windings 79.

Means is provided for operating the handles of the circuit breakers from outside the tank or housing 25. As shown in FIG. 4, this means comprises a manual operator 191 xed on a hollow shaft 192 which extends through the side wall of the tank and is connected by a rod 193 to the breaker handles 65, lthe handles being suitably tied together for simultaneous operation.

The hollow shaft 192 has at its outer end a lens and signal light 195 connected by conductors 197 extending through the hollow shaft to the signal light switch 169 and to a secondary winding on the core 77 of the transformer. The secondary winding for energizing the signal light is preferably an additional secondary winding 81, but in some cases the light may be energized from the main secondary winding 79.

The tank 25 of the transformer is lled with oil or other insulating medium to a level above the bimetal elements, so that the bimetals are responsive not only to the current flow in them, but also to the temperature rise of the transformer as reflected by the temperature rise of the oil. This protects the transformer against gradual overheating by small overloads sustained for a long period of time.

The bimetal elements 103 (FIG. l) may be adjustable from outside the tank to permit the circuit breakers to be closed and latched immediately after a tripping operation without waiting for the large mass of the transformer to cool, and to permit the circuit breaker to temporarily carry an emergency load of a certain percentage of overload current for a predetermined time. The means for adjusting the bimetal elements 103 comprises pivotal mounting of the bimetals and the adjusting screws 127. Mounted on the adjusting screws 127 for each of the breakers in an arm 225 (FIGS. l and 3) of insulating material having an opening forming a non-slip but adjustable connection with serrations on the screws 127. The insulating arms 225 of the breaker units are connected by means of a link 227 (FIG. 3) for unitary movement and the operating wire 228 of a Bowden cable 229 is attached to one of the arms 225. The cable 229 is tightly secured by means of a clamp 231 and a screw 233 to the housing 11 of one of the breakers. The other end of the cable 229 is securely held in a bracket 230 (FIG. 4) mounted on the inside of the tank wall. The operating wire 228 of the Bowden cable is attached to an arm 232 of an operating device 238 mounted on a shaft 234 at the inside of the tank. The

* shaft 234 extends out through a sealed bearing in the tank Wall and has an emergency operating handle 236 secured to the outer end thereof.

Operation of the emergency handle 236 acts through the Bowden cable 229 in a well known manner to simultaneously rotate the arms 225 and the adjusting screws 127 (FIGS. 1 and 3). Movement of the adjusting screws 127 (FIG. l), each of which threadedly engages the corresponding adjusting rod 125, causes rotation of the arm 121 and the yoke 11S on which the bimetal element 103 is mounted about the pivot 117. This moves the latch portion to a latching position even though the bimetal remains hot and in deflected condition and permits relatching of the mechanism and closing the breaker. By this emergency adjustment, the breakers will carry a given overload for a predetermined time but will trip out in response to a higher overload, or short circuit currents. Raising the calibration of the breaker by turning the screws 127 also raises the point at which the indicating or signal member 147 is released, since it is held by the same latch portion 100 as the tripping actuator 93 and is released by the latch portion 100 prior to the actuator 93.

Under certain conditions or in an extreme emergency it is desirable that the circuit breaker shall remain closed to keep the transformer in service even though there exists an overload current condition which would ordinarily trip the breaker open. The use of non-trip-free circuit breakers which could maintain the circuit closed by holding the handle is not satisfactory because the important and desirable advantages of the trip-free circuit breaker are lost under normal conditions. Furthermore, it is desirable that it be possible to set the breaker for normal trip-out where the maintaining of service is not critical.

In order to maintain service in critical areas and in extreme emergencies, means is provided to positively prevent the circuit breaker from tripping out. This means comprises an interposer or locking arm 235 (FIG. 1) pivoted on the pin 113 and having a pin and slot connection 237 with an operating rod 239. The locking arm 235 is provided with a ilatching or interposing end 241 adapted to be moved into the path of tripping movement of the trip actuator 93 so as to be engaged by the yoke portions 111 of the actuator and prevent tripping operation of the actuator 93. The operating rod 239 extends outwardly through an opening in the housing 11 and threadedly engages a nut 243 which is rigidly fixed in the bore of an operating arm 245. Also rigidly mounted in the bore of the arm 245 is a nut 247 which is threadedly engaged by an adjusting screw 249 held in its adjusted position by a spring grip retainer 251. A compression spring 253 (FIG. l) biases the operating rod 239 together with the interposer 235 and the operating arm 245 downward so that the hub 255 of the operating arm 245 bears against a metal washer 257.

The direction of the thread of the operating rod 239 is such that counterclockwise rotation of the operating arm 245, as viewed in FIG. 3, and the nut 243 moves the operating rod 239 downwardly causing counter-clockwise movement of the interposer 235 to position the end 241 thereof in position to block tripping movement of the trip actuator 93. Reverse movement of the arm 245 raises the rod 239 and withdraws the interposer 235 from its blocking position and restores the circuit breaker to its trip-free automatic condition.

The operating arms 245 (FIG. 3) of the several circuit breaker poles are connected for simultaneous movement by a link 259 which is pivotally connected to the arms 245 by pivot pins 261. The end of the operating wire 263 of a Bowden cable 265 is connected to the link 259 and the cable 255 is held against movement by means of a clamp 267. The clamp 267 is rigidly mounted on a plate 269 by suitable fastening means 271. The plate 269 is mounted on surfaces 273 of the breaker housing 11 and is rigidly held in place by spring grip retainers 275 surrounding and engaging the bimetal adjusting nuts 127. The spring grip retainers 275 are provided with formed over fingers 277 which engage in openings in the plate 269 to prevent them from turning. The other end of the Bowden cable 265 is fixedly held by the bracket 240 (FIG. 4) and the operating wire 263 is connected to be operated by a trip-preventing operating device 243 like the device 23S for operating the emergency adjusting means for the bimetals. The device 248 comprises an arm 242 to which the wire 263 is attached. The arm 242 is fixed on the inner end of a shaft 244 on the outer end of which is mounted a handle 246.

It is an important feature of the transformer invention disclosed herein that operation of the trip-preventing operating device 248 at the outside of the transformer tank 25, acts to prevent opening of the breaker contacts without interfering with, and independently of, the operation of the signal or indicating device 195 controlled by the contacts 163-169- This desirable result is obtained because the latching or blocking end 241 of the locking arm 235 is in the path of movement of the yoke 111 of the trip actuator 93, but does not interfere with movement of the signal operating member 147. Thus, when the trip-preventing handle 248 is actuated to block tripping of the breaker, there is no change in the calibration yor operation of the signaling device and the light 195 at the outside of the transformer will indicate the presence of an overload condition on the transformer, the same as if the trip-preventing handle 248 had not been actuated to blocking position. It is also of importance, first, that the circuit breaker contact-operating handle 191 at the outside of the transformer may be operated while the trip-preventing handle 248 is in blocking position so that the circuit breaker may be manually operated as a switch; and secondly, that the circuit breaker operating handle 191 may be operated to reset the signal light switch 163- 169 and put out the light 195 on the tank of the transformer after there has been an overload condition Without opening the circuit breaker contacts and causing an interruption in the power supplied by the transformer.V This makes it possible for the light of the transformer to be used to indicate both the presence of an overload condition, and by resetting it one or more times without opening the circuit, to indicate if the overload has disappeared -or if it has continued to exist or occurred again.

The invention also provides a novel circuit breaker which, with the several manual setting devices in their normal positions functions as a trip-free circuit breaker to trip the breaker open in response to overload currents and give a signal that the breaker has tripped open or that a dangerous overload exists, which can be set to carry a certain overload current for a predetermined time in emergencies, and which can be set to block tripping thus converting the breaker into a switch in the case of a critical installation extreme emergency.

Having described the invention in accordance with the provisions of the patent statutes, it is to be understood that various changes and modifications may be made in the structural details thereof Without departing from the spirit of the invention.

I claim as my invention:

1. A circuit breaker comprising relatively movable contacts and operating means therefor, latch means movable to a tripping position to effect automatic opening of said contacts, stored energy means releasable to engage and move said latch means to said tripping position, a trip device comprising a thermally responsive element releasably restraining said stored energy means and operable in response to overload currents to release said stored energy means, and an interposer movable to a position to block tripping operation of said stored energy means to thereby prevent automatic opening of said contacts.

2. In a multipole circuit breaker, relatively movable contacts in each pole, operating means in each pole releasable to effect automatic opening of the contacts of the associated pole, latch means releasably restraining said operating means and movable to release said operating means, stored energy means in each pole operable when released to engage the associated latch means and move the latch means for all of the poles to effect release of the operating means for all of the poles, a thermally responsive element in each pole releasably restraining the associated stored energy means, means comprising an interposer in each pole each movable to a position to individually block tripping movement of the stored energ means for the associated pole to thereby prevent automatic opening of said contacts.

3. In a multipole circuit breaker, relatively movable contacts in each pole, operating means in each pole releasable to effect opening of the contacts of the associated pole, latch means releasably restraining said operating means and movable to release said operating means, stored energy device in each pole operable when released to engage the associated latch means and move the latch means for all of the poles to effect release of the operating means for all of the poles, a thermally responsive element in each pole releasably restraining the associated stored energy device, means comprising an interposer in each pole each movable to a position to individually block tripping movement of the stored energy device for the associated pole, and means for simultaneously moving all of said interposers to blocking position to thereby prevent automatic opening of said contacts.

4. In a multipole circuit breaker, relatively movable contacts in each pole, operating means in each pole releasable to effect opening of the contacts of the associated pole, latch means releasably restraining said operating means and movable to release said operating means and cause tripping movement of all of the poles, a bimetal element in each pole, means comprising an interposer in each pole each movable to a position to individually block tripping movement of the associated pole, means simultaneously moving all of said interposers to blocking position to prevent release of said operating means and automatic opening of said contacts While permitting defiection of said bimetal element, and adjusting means for indi- 9 vidually adjusting the initial position of each of said interposers.

5. A multipole circuit breaker comprising a releasable switch arm for each pole, each of said switch arms having a movable contact on one end and a latch releasably supporting the other end, a Ireleasable stored energy device for each pole, each of said releasable stored energy devices being operable when released to engage and actuate the latch for the associated pole to effect automatic opening movement of the associated switch arm, a trip bar interconnecting the latches for all of said poles so that upon release of the stored energy device for any one of said poles the latches for all of the poles are operated to effect release of all of said switch arms, a thermally responsive element for each pole heated in response to overload currents in the circuit of the associated pole and operable when heated a predetermined amount to release the corresponding stored energy-device, adjusting means for each of said thermally responsive elements, means interconnecting the adjusting means for all of the poles for effecting simultaneous adjustment of all of said thermally responsive elements to permit said stored energy device to be reset and permit said switch arms to -be closed while said bimetal elements are hot, and an interposer in each pole each being movable to a position to block tripping movement of the associated stored energy device to thereby prevent automatic opening movement of said switch arms.

6. A multipole circuit breaker comprising a releasable switch arm for each pole, each of said switch arms having a movable contact on one end and a latch releasably supporting the other end, a releasable latch actuator for each pole :operable when released to engage and actuate the latch for the associated pole to effect automatic opening movement of the corresponding switch arm, a trip bar interconnecting the latches for all of said poles so that upon release of the latch actuator for any one of said poles the latches for all lof the poles are operated to effect release of all of said switch arms, a bimetal element for each pole heated in response to overload currents in the circuit of the associated pole and operable when heated a predetermined amount to release the corresponding latch actuator, adjusting means for each of said bimetal elements, means interconnecting the adjusting means for all of the poles for effecting simultaneous adjustment of all of said bimetal elements to permit said latch actuators to be reset and permit said switch arms to be closed while said bimetal elements are hot, and an interposer in each pole each being movable to a position to block tripping movement yof the associated latch actuator to thereby prevent automatic opening movement of said switch arms, manual means in each pole for manually moving the associated switch arm to open and closed positions, and means interconnecting said manual means for simultaneously moving all of the switch arms to open and closed positions regardless of the blocked condition of said latch actuators.

'7. A circuit breaker comprising relatively movable contacts, operating means therefor, latch means movable to a tripping position to effect automatic opening of said contacts, indicating means, a thermally responsive element movable in one direction to one position to cause actuation of said indicating means and movable in the same direction to a further position to actuate said latch means to effect automatic opening of the relatively movable contacts, a manually operable member having a set position in which said indicating means is actuated when the thermally responsive element has moved to said one position, and said manually operable member when in said set position acting to prevent automatic opening of the relatively movable contacts even though the thermally responsive element has moved to said further position.

8. A circuit breaker comprising relatively movable contacts, operating means therefor, latch means mova-ble to a tripping position to effect automatic opening of said contacts, indicating means, a thermally responsive element movable in one direction to one position to cause actuation of said indicating means and movable in the same direction to a further position to actuate said latch means to effect automatic opening of the relatively movable contacts, a manually movable Contact operating member for manually opening and closing the relatively movable contacts, a manually movable trip preventing member having one set position in which automatic tripping of the breaker is prevented even though the thermally responsive element has moved to its said further position without said trip preventing member preventing actuation yof said indicating means when the thermally responsive element has moved to said one position, and said contact operating member being manually movable to open and close the relatively movable contacts while said trip preventing member is set in its position to prevent automatic tripping of the breaker.

9. A circuit breaker comprising relatively movable contacts, operating means therefor, latch means movable to a tripping position to effect automatic opening of said contacts, indicating means, a thermally responsive element movable in one direction to one position to cause actuation of said indicating means and movable in the same direction to a further position to actuate said latch means to effect automatic opening of the relatively movable contacts, a manually movable contact operating member for manually opening and closing the relatively movable contacts, means operable by manual movement of said contact operating member to reset said indicating means to non-indicating position without opening the relatively movable circuit breaker contacts, a manually movable trip preventing member having one set position in which automatic tripping of the breaker is prevented even though the thermally responsive element has moved to its said further position without said trip preventing member preventing actuation of said indicating means when the thermally responsive element has moved to said one position, said contact operating member being manually movable to reset said indicating means while said manually movable trip preventing member is set in its position to prevent automatic tripping of the breaker, and a third manually movable member operable externally of the circuit breaker to raise the calibration at which said thermally responsive element both actuates said indicating means and effects automatic opening of the relatively movable contacts.

1t). A circuit breaker comprising relatively movable contacts and means releasable to effect opening of said contacts, restraining means normally releasably restraining said releasable means, stored energy means releasable to engage and cause said restraining means .to release said releasable means, a thermally responsive element releasably restraining said stored energy means :and operable in response to predetermined abnormal conditions to release said stored energy means, and a member movable to a position to prevent operation of said stored energy means.

11. A circuit breaker comprising relatively movable contacts and means releasable to effect opening of said contacts, restraining means normally releasably restraining said releasable means, sto-red energy means releasable to engage and cause said restraining means to release said releasable means, a thermally responsive element releasably restraining said stored energy means and operable in response to predetermined abnormal conditions to release said stored energy means, and a member movable to a position to prevent operation of said storedenergy means while permitting unrestrained movement of said thermally responsive element.

12. A circuit breaker having manually resettable means for automatically tripping said breaker open, means for manually opening and closing said breaker, indicating means, manually resettable means for automatically tripping said indicating means to an indicating condition before said breaker trips open, and manually operable means mounted on said circuit breaker and manually 2,246,890 6/41 Miller 317-15 movable into locking position with said automatic tripping 2,356,055 8/ 44 Hodnette 317-14 means for locking said breaker tripping means in its reset 2,490,073 12/ 49 Malone 200-138 Condition Without affecting the operability of all said 0th- 2,650,356 8/ 5 3 Stein 340-227 er means. 5 2,726,299 12/55 Carlson 200-138 2,892,127 6/59 Leonard 317-15 References Cited by the Examiner 2,924,689 2/ 60 Edmunds 200-114 UNITED STATES PATENTS SAMUEL BERNSTEIN, Primary Examiner. 799,790 9/05 H1ll1ard 317-35 1,005,445 10/11 Maik 317-35 10 

1. A CIRCUIT BREAKER COMPRISING RELATIVELY MOVABLE CONTACTS AND OPERATING MEANS THEREFOR, LATCH MEANS MOVABLE TO A TRIPPING POSITION TO EFFECT AUTOMATIC OPENING OF SAID CONTACTS, STORED ENERGY RELEASABLE TO ENGAGE AND MOVE SAID LATCH MEANS TO SAID TRIPPING POSITION, A TRIP DEVICE COMPRISING A THERMALLY RESPONSIVE ELEMENT RELEASABLY RESTRAINING SAID STORED ENERGY MEANS AND OPERABLE IN RESPONSE TO OVERLOAD CURRENTS TO RELEASE SAID STORED ENERGY MEANS, AND AN INTERPOSER MOVABLE TO A POSITION TO BLOCK TRIPPING OPERATION OF SAID STORED ENERGY MEANS TO THEREBY PREVENT AUTOMATIC OPENING OF SAID CONTACT. 